<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
  alert(11)
  var shuzu=[[1],[2],[3]]
  for(var i=0;i<shuzu.length;i++){

    console.log(shuzu[i][0])
  }
  alert(11)
</script>
</body>
</html>
